As is well known, lawn mowers are utilized to keep lawns, gardens and grassy areas in general, in optimal condition, that is, to keep the grass below a certain height in a substantially homogenous manner throughout the entire cutting area.
The cutting area is often delimited by a perimeter wire or cable, in which an electrical signal is propagated; the lawn mower, detecting this electrical signal, is capable of recognizing its own (internal/external) position with respect to the cutting area, and adjusts its movement accordingly.
A first solution made available by the prior art foresees that the electrical signal in the perimeter cable has a mono-frequency sinusoidal waveform.
When starting operation, the lawn mower is synchronized with the management device, that is, the device that provides for the generation of the electrical signal cited, and stores a representative reference value of this sinusoidal signal.
During operation, the lawn mower detects, by means of suitable sensor means, the signal propagated in the perimeter cable, and compares the signal detected with the reference value stored previously in the memory.
If the two signals match, the lawn mower “understands” that it is within the cutting area; vice versa, if the two signals differ, the lawn mower recognizes that its position is outside of the cutting area. In both cases, the information obtained is useful for regulating the movement and/or cutting operations of the lawn mower itself.
The main drawback of this first configuration emerges with regard to the system's energy consumption. In fact, propagation of the electrical signal is substantially continuous, actually resulting in levels of energy consumption that are not negligible.
A second prior-art solution consists in the utilization of a current signal having at least two different harmonic components.
During operation, the lawn mower detects this signal, separates the two harmonic components and based on the latter, it determines whether it is inside or outside the cutting area.
In this case as well, the information is then utilized to control the execution of movement and/or cutting operations on the part of the lawn mower.
The main drawback related to this second solution consists in the fact that it involves a complicated technique, which requires the presence of complex and costly circuits on board the lawn mower.
Moreover, a further drawback is related to the generation of harmonics, which, as is known, create interference affecting other machines in the vicinity of the work area.
The aim of the present invention is to make available an apparatus for cutting grass in which the lawn mower is able to determine in a simple and reliable manner its (internal/external) position with respect to the cutting area.
An additional aim of the present invention is to make available an apparatus for cutting grass in which the lawn mower is able to regulate its own movement and the cutting operations in a simple and reliable manner.
An additional aim of the present invention is to make available an apparatus for cutting grass in which the lawn mower is capable of operating in a correct and efficient manner, and, at the same time, has a simple and economical electronic structure.
A further aim is to make available an apparatus for cutting grass that is capable, during operation, of not causing interference affecting other machines located in the vicinity of the work area.